Incremental reindexing during upgrade of large gerrit site

In order to shorten the downtime needed to reindex changes during a Gerrit upgrade the following strategy can be used:

• index preparation
  • create a full consistent backup
  • note down the timestamp when the backup was created (backup-time)
  • create a complete copy of the production system from the backup
  • upgrade this copy to the new Gerrit version
  • online reindex this copy
• upgrade of the production system

  • make system unavailable so that users can't reach it anymore e.g. by changing port numbers (downtime starts)

  • take a full backup

  • run

    ./reindex.py -u gerrit-url -s backup-time
    

    to write the list of changes which have been created or modified since the backup for the index preparation was created to a file “changes-to-reindex.list”

  • upgrade the production system to the new gerrit version skipping reindexing

  • copy the bulk of the new index from the copy system to the production system

  • run

    ./reindex.py -u gerrit-url
    

    this reindexes all changes which have been created or modified after the backup was taken reading these changes from the file “changes-to-reindex.list”

  • smoketest the system

  • make the production system available to the users again (downtime ends)

Online help

For help on all available options run

./reindex -h

Python environment

Prerequisites:

• python 3.9
• pipenv

Install virtual python environment and run the script

pipenv sync
pipenv shell
./reindex <options>